Lack of interaction between α2-adrenoceptors and dopamine D2-receptors in mediating their inhibitory effects on [3H]dopamine release from rat nucleus accumbens slices

Russell V.A.
Lamm M.C.L.
Taljaard J.J.F.
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The α2-adrenoceptor agonist, UK14304, dose-dependently inhibited the electrically stimulated release of dopamine (DA) from rat nucleus accumbens slices. This effect was antagonized by idazoxan, confirming that it was an α2-adrenoceptor mediated effect. There was no evidence of endogenous activation of noradrenergic receptors suggesting that the α2-adrenoceptor agonist was not acting presynaptically to inhibit noradrenaline release. An in vitro superfusion technique was used to investigate whether there was any interaction between α2-adrenoceptors and DA D2-receptors in mediating their inhibitory effects on [3H]DA release from rat nucleus accumbens slices. α2-Adrenoceptors and DA D2-receptors interact with similar second messenger systems and it was considered that they may compete for a common pool of G-proteins. The inhibitory effects of the α2-adrenoceptor agonist, UK14304, and the DA receptor agonists, quinpirole, apomorphine and pergolide were not independent. However, there was no evidence of any interaction between UK14304 and the DA D2-receptor antagonists, sulpiride or haloperidol, suggesting that the two receptors do not compete for a common pool of G-proteins in mediating their inhibitory effects on DA release.
alpha 2 adrenergic receptor, apomorphine, brimonidine, citalopram, desipramine, dopamine, dopamine 2 receptor, dopamine receptor blocking agent, dopamine receptor stimulating agent, guanine nucleotide binding protein, haloperidol, idazoxan, pergolide, quinpirole, sulpiride, tritium, animal tissue, article, brain slice, depression, dopamine release, male, nonhuman, nucleus accumbens, priority journal, rat, signal transduction, tissue perfusion, Adrenergic alpha-Agonists, Animal, Apomorphine, Binding, Competitive, Dopamine, Electric Stimulation, Ergolines, GTP-Binding Proteins, Haloperidol, In Vitro, Male, Nucleus Accumbens, Pergolide, Quinoxalines, Quinpirole, Rats, Rats, Wistar, Receptors, Adrenergic, alpha, Receptors, Dopamine D2, Signal Transduction, Sulpiride, Support, Non-U.S. Gov't
Neurochemical Research